At present, in mining operations in Chile and around the world, the exchange of dump bodies of mining trucks and bodies of water trucks is performed with the suspended load working method, using one or two high tonnage loading cranes, equipped with heavy lifting devices.
The state of the art shows two patent applications submitted in Chile, numbered 200302430 and 200701876, which publish a mining truck dump body lifting system comprising four adjustable columns, comprising a vertical traveling support arm; main function of the system is the mounting and dismounting of mine truck bodies; replacing the concept of suspended load and introducing the concept of supported load. In the second patent application, number 200701876, the mining truck dump body lifting system published comprises six adjustable columns. In this system, the two central columns rotate 180°, allowing the operation in two adjacent working areas.
In both systems described in these patent applications, operational risks posed by the vertical and horizontal movements of the columns were identified. Should the lifting column hydraulic cylinder fail to operate, the worker would need to access the vertical traveling support arm climbing up in a ladder up to the position of the vertical traveling support arm and then triggering a mechanical locking system with the inherent risk of dump body falling on the operator and/or the operator falling down from height; for these reasons this invention now comprises automatic mechanical safety locks in each column with the purpose of preventing the horizontal and vertical movements of the column; triggering of these locks is made from the base of each column.
Another concern on the prior art relates to the positioning and horizontal movement of the column as the systems published in patent applications numbers 200302430 and 200701876 only include hydraulic locking valves, which in case of failure, do not prevent the horizontal hydraulically-driven movement of the central rotating column under load. For this reason, this invention now comprises load sensors in each column, connected to the lifting system, for the purpose of detecting and locking any horizontal movement of columns under load, thus also preventing an operator from activating a horizontal movement with the columns under load. This sensor is located in the hydraulic lifting system and blocks the horizontal movement.
Also, the frequent use of the 180° toothed crown of the turntable in the central rotating column, results in a quick wear of turntable bearing teeth thus requiring shutting down the lifting system for servicing or repairing worn out parts.
With the purpose of providing a solution to the above mentioned concerns, the design includes a central column allowing a 360° rotation on its central axis, also comprising mechanical safety locks and load sensors for a safe operation in vertical and horizontal movements.